Coast-to-coast solar plane flight set for May 1

San Francisco to New York, with three stops in between—at 43mph.

For many years now, Swiss adventurer and balloonist André Borschberg has been working on an experimental solar-powered plane, which made its maiden flight in 2009.

Since a test showing that the Solar Impulse could stay aloft using solar power and solar-charged batteries, Borschberg has made test flight (Switzerland, 2010) after test flight (Madrid to Rabat, 2012), at ever-increasing distances.

Borschberg now has his sights set on the United States and is planning a cross-country, five-stage promo tour that will go from San Francisco to New York by way of Phoenix, Dallas, and Washington DC. The tour is set to begin on May 1—the plane will spend 10 days in each location to teach students and pilots about solar powered-flight.

While the $112 million plane is fully capable of crossing the United States nonstop (which would take three days, given its limited speed of 43 miles per hour—about one-tenth the speed of commercial airliners), it’s unable to due to “security reasons.”

"We would like to inspire students, schoolchildren, inspire as many people as possible to try to have the spirit to dare, to innovate, to invent,” Bertrand Piccard, Solar Impulse’s president and co-pilot said at a press conference in Mountain View, California on Friday.

"The question is not to use solar power for normal airlines," Piccard told reporters last year. "The question is more to demonstrate that we can achieve incredible goals, almost impossible goals, with new technologies, without fuel, just with solar energy, and raise awareness that if we can do it in the air, of course everybody can do it on the ground."

It can take off at 27 mph (44 km/h) and maintain the average speed of 43 mph (70 km/h) with a weight of 3,527 lb (1600 kg) from 11,628 monocrystalline silicon solar cells of which 10,748 are on the wings at a wingspan of 208 ft (63.40 m).

Quote:

At midday, each square meter of land surface receives, in the form of light energy, the equivalent of 1000 watts, or 1.3 horsepower of light power. Over 24 hours, this sun energy averages out at just 250W/m². With 200m² of photovoltaic cells and a 12 % total efficiency of the propulsion chain, the plane’s motors achieve an average power of 8 HP or 6kW.

plane is fully capable of crossing the United States nonstop ..., it’s unable to due to “security reasons

Kind of curious what the security reasons are that they're referring to here.

Me too. I assume it's a total red herring. a 40-50mph 1.6 ton airplane isn't much of a security threat, and whether it flies across the continent in 3 days or 300 days makes no change to its "threat level." Either this is BS, or someone in authority is being unreasonable/irrational.

Seriously neat. Seriously. I just doubt this will ever evolve into commercially viable craft. I just don't see how a solar craft can generate enough thrust to fly tens or even hundreds of people across the ocean in reasonable time. Maybe for short local distances? But still too slow. Unless the fares are really cheap.

However, even this remains in experimental state, it should contribute significantly to development of solar tech and efficient craft design in general.

plane is fully capable of crossing the United States nonstop ..., it’s unable to due to “security reasons

Kind of curious what the security reasons are that they're referring to here.

My guess is that in order to stay in the sun belt and avoid certain mountains they might have to fly over some of the larger military bases.

As someone who's flown large RC aircraft and rockets (solid and liquid fueled) for 40+ years, I can tell you that DHS, ATF, and the FBI...at the least...aren't very tolerant of what they term 'potential weapons' flying anywhere near lots of places.

Locally, if my P-51D with a 6 foot wingspan exceeds 400', the guys from the nearby AFB get upset. Launching rockets locally is not even possible; we have to literally go to the middle of nowhere for anything larger (payload capable) than tiny Estes Mylar / balsa solid fuel models.

"This airplane could do it nonstop," said co-pilot and project CEO André Borschberg, "but because the pilot is not as sustainable as the technology, we have limited ourselves to 24-hour flight duration."

Apparently falling asleep and crashing a solar powered plane is a bad idea, who would have thought?

"This airplane could do it nonstop," said co-pilot and project CEO André Borschberg, "but because the pilot is not as sustainable as the technology, we have limited ourselves to 24-hour flight duration."

Apparently falling asleep and crashing a solar powered plane is a bad idea, who would have thought?

Bleh. I know the "power from sunlight" thing sounds cool, but "peak conversion" only happens for a short time when the sun is directly overhead. For about half of the daylight flight time, the angle on those panels is going to be too low, probably below 50% rated output. That means batteries will not fully recharge.

I'm sure a high-altitude unmanned drone could make the flight (at least in the direction of the slip stream) but the energy needed for a manned, sustained cross country flight is still beyond what panels alone can provide.

I just realized the irony... flying with a tail wind means you shorten the peak output time because your flying against the path the sun travels. Better to fly in the southern hemisphere where you have east to west tail wind. Flying over the Amazon river even gives some extra "eco cred" lol.

"This airplane could do it nonstop," said co-pilot and project CEO André Borschberg, "but because the pilot is not as sustainable as the technology, we have limited ourselves to 24-hour flight duration."

Apparently falling asleep and crashing a solar powered plane is a bad idea, who would have thought?

Uhmm, why hasn't anyone done this with both solar and helium to stay aloft?I would assume that would give the ultimate result.

I would think using helium would dramatically increase the aircraft's size, and reduce its speed. Since it can be flown without it, why would we need to add helium to the equation? It would only be useful for generating lift, but if the aircraft can already travel fast enough it can easily generate enough lift with the airfoil.

"This airplane could do it nonstop," said co-pilot and project CEO André Borschberg, "but because the pilot is not as sustainable as the technology, we have limited ourselves to 24-hour flight duration."

Apparently falling asleep and crashing a solar powered plane is a bad idea, who would have thought?

My employer is one of the primary sponsors of this aircraft so I've been hearing about this for quite some time.

Regarding the security, I'm not sure exactly why it's being treated the way it is, I don't think there's any classified technology in it. However I do know that it is being launched in SF from an airforce base, and anyone attending the event had to have a very thorough background check to enter the base.

The stops have been planned for a long time, and it's been flying around Europe for quite some time already. Additionally, once it makes the trip across the US, they plan on having it do a 'round the world flight non-stop, probably in 2014 or 2015.

Some more info

Quote:

Solar Impulse HB-SIA is the first aircraft that can fly day and night without fuel or polluting emissions. It demonstrates the huge potential of new technologies in terms of energy reduction and the production of renewable energy. This revolutionary carbon fibre aircraft, that has the wingspan of an Airbus A340 (63.4m) and the weight of an average family car (1,600kg), is the result of seven intense years of work, calculations, simulations and tests by a team of 70 people and 80 partners. A plane this light and of this size has never been built before. The 12,000 solar cells built into the wing provide four 10HP electric motors with renewable energy. By day the solar cells recharge the 400kg lithium batteries which means the plane can fly at night.

they plan on having it do a 'round the world flight non-stop, probably in 2014 or 2015.

"Non-stop"?

Is that realistic? Among the many logistics, that requires at least two pilots and all the associated provisions. That, plus batteries for night flying. Either this technology is far more advanced than I can imagine, or you have a different definition of 'non-stop'.

(I'm not trying to be negative, but am curious about how this could possibly be done.)

Uhmm, why hasn't anyone done this with both solar and helium to stay aloft?I would assume that would give the ultimate result.

I would think using helium would dramatically increase the aircraft's size, and reduce its speed. Since it can be flown without it, why would we need to add helium to the equation? It would only be useful for generating lift, but if the aircraft can already travel fast enough it can easily generate enough lift with the airfoil.

True, the extra lift might slow down the aircraft. But the non oil, rare earth metals and magnets used for the motors in the propellers to make this on a useful human/industrial scale might be costly.Hellium, although wasted everyday, would be cheaper, assuming it's not to expensive to nano coat a light weight balloon.Crap, you could even wind sail it if you were to go completely motorless....

Could this technology be practical for cheap short range journeys any time soon? Or do we still need to wait awhile for far more advanced solar technologies?

The answers are:1. No.2. Never going to happen.

Solar powered planes are utterly impractical. The energy available from sunlight is just too low. Even if you assume magic, never going to exist 50% efficient solar panels*, its still too low to do anything useful.

*Yeah, yeah, some guys in a lab made whatever. Show me a viable plan for production solar panels even close to this.

Also what's all this business about this thing flying "non-stop" I'm not even going to bother doing the math before I declare that impossible. At the cruising speed of this thing, the trip will take more than 1 day. And there is no way, in any imaginary battery technology, that you could both collect enough energy to fly it during the day AND store enough to fly it through the night.

So what nonsense are they spewing here? Or is it a "Solar powered plane" except when they fire up the gasoline generators at night?